The invention pertains to storage containers in general and, more particularly, a container for samples which serves for entrapping, storage, transportation and processing of a system of analyzed compounds from withdrawal of each sample from its source until the actual analytical determinations. The storage container, according to the invention, can be employed for general chemical and clinical analyses; in toxicology; for environmental inspections; in water analyses; in agriculture; the foods industry; analyses of biologic samples and in biotechnology.
The storage and transportation of samples before analysis, as well as methods for the isolation of a system of compounds for a final analysis, represent a considerable problem requiring a great deal of the total alloted time for determination from the viewpoint of technique and method. It is, therefore, an imperative demand of each modern method of determination to reduce the time necessary for chemical, radiochemical or instrumental analysis, since the periods required for the determination of quantities of investigated components in a properly prepared sample are minutes to tens of minutes.
The commonly employed methods of sample processing, which are based upon extraction techniques and the subsequent concentration of the mixture by evaporation of solvents, require large quantities of pure solvents, laboratory glassware and energy, and are very labor-intensive in general. Also, the transportation of withdrawn samples in an original state from the place of sample taking to the place of analysis can be time consuming and costly, with the further problem that the composition of the sample may change while it is being transported. Mention may be made, by way of example, of special analyses of urine samples, which are carried out in only a few specialized laboratories in large towns of Czechoslovakia, withdrawing and determination of trace contaminants in waste or surface waters, and withdrawing and determination of radioactive or highly toxic materials from fields.
A critical evaluation of time and expense for a single analytical determination in a real sample reveals that a final analysis by means of a modern instrumental technique is less time consuming and less expensive than the previously known operations for entrapping, storage, transportation and processing of samples. Relatively little attention has been given to this problem, which represents a genuine need in the art, and which is now solved by means of the present invention.
In comparison with the known extraction methods, the technique of sorption on the solid surface of a sorbent presents numerous advantages, above all for the determination of very small concentrations of investigated compounds, where a perfect purity of extraction agents plays a decisive role, with regard to the volumes applied, in the potential for contamination of the sample during its preparation. A known system in the United States for concentration of compounds is SepPac.RTM. of Waters Co., which consists in utilization of a radially compressible plastic material for preparation of tubes containing a solid sorbent. A disadvantage of this known process, however, is the relatively expensive special plastic material the production of which requires a special processing technology. This fact is reflected in the relatively high price of the product. Other disadvantages relative to the object of the present invention are the hydrodynamic conditions during entrapment of a sample in the tube and its desorption, and also the danger of a subsequent contamination of absorbed sample through open inlet and outlet means of the tubes during long storage periods. Moreover, the choice of sorption materials is limited to two fundamental sorbents in the known system. Similar characteristics are associated with the concentration precolumn and sorbents produced by Merck Co., FRG, under the trade name Extrelut.RTM..
It is, therefore, an object according to the present invention to provide a fast and inexpensive technique for sample determinations, free from the defects and disadvantages of the known techniques.